1. Field of the Invention
This invention relates generally to an improved U-clip and more specifically to an assembled arrangement of such clips which are abuttingly suspended in a continuous fashion on a carrier strip of pliant material so that the clips can be easily stored or used in a clinching tool, where the tool secures juxtaposed wires together.
2. Description of the Prior Art
U-clips have been well known and used with clinching tools in various fields such as upholstery or the mattress and bedding industries where either two wire springs, or a spring and a border retaining wire are secured together.
The U-clips are typically aligned and collated in a stacked configuration so that each individual clip is similarly arranged in abutting relationship with the adjacent clip. Clips arranged in a stacked configuration facilitate neat and orderly storage, as well as providing a linear alignment that is especially adapted for rapid and successive feeding of clips into a reformation or clinching tool which is positioned over a pair of parallel wires.
Stacks of clips can be wound under tension around a cylindrical core member, much like a spool of string, and then stored by packaging the spools in a shipping or storage carton. When an individual stack of clips is to be used, it is unwound under tension, beginning with the free end, and then the free end is inserted into the clinching tool in a linear fashion so that clamping together of at least two juxtaposed wires can occur. Most clips are retained in the collated stacks by employing various clip designs in conjunction with various retention means, such as adhesive tapes, or dimpled, grooved, or troughed clips which receive metallic wires, plastic filaments, or the like.
Because of the manufacturing requirements for high speed and uninterruptable feeding, the clip retention means must have a requisite flexibility and strength for withstanding the spool winding and unwinding forces, as well as feeding of the clinching tool. Furthermore, it is a desire not to incorporate a clip retention means which will ultimately affect or interfere with the clamping of the clip around the wires to be joined.
Various solutions have been previously proposed for interconnecting clips, such as U.S. Pat. No. 3,722,670 in which a clip assembly employs an elongated strand of plastic filament frictionally inserted into a preformed notch on each lateral side of the clip. However, this friction-fit arrangement has a tendency to dislodge the clip from the notch when spooling/unspooling tension forces are applied.
Other proposals, like that of U.S. Pat. No. 4,508,220, incorporate a very small diameter wire as the filament binding means. However, a shortfall of this method of assembly is that it requires the wire filament to be welded to the clip. Furthermore, once the wire filament is severed by the clinching tool, sharp, abrasive wire ends are exposed to the worker and the workpiece.
The U.S. Pat. No. 5,314,065 sought to overcome the above mentioned shortfalls by providing a clip with a plastic filament that was positively, rather than frictionally held against the side of the clip. This disclosure presents a rather complicated U-clip, wherein a filament-anchoring tab on each clip side is simultaneously compressed downwardly in order to positively attach the parallel filaments to the clip. Locating the filament-catching tabs along the sides of the clip, exposes a multitude of edges on each tab, causing collated clips to entangle with each other. When this happens, continuous unwinding and feeding of a spool of clips becomes problematic if not impossible. Another shortfall of this clip is that material is punched-out from the blank when forming the tabs; this weakens the clip. This methodology also wastes material and requires additional, and expensive tooling. Furthermore, the tab locations cause the filament strips to bridge across the legs of the clip and extend into the wire receiving cavity area of the clip, thereby interferring with the insertion of the wires into the clip cavity.
As evidenced by the shortfalls of the above-mentioned methods and apparatus, a true need still exists for an improved and simple U-clip and method for interconnecting such clips, wherein the identified shortcomings are overcome by providing a positive and flexible interconnection that does not extend into the wire-receiving cavity and which does not add complicated manufacturing tooling and control functions to the forming process, or undue additional costs.